NEET · Biology · Molecular Basis of Inheritance doubts
20 doubts found
What does “DNA structure” actually mean in Molecular Basis of Inheritance, and why does it matter for NEET?
a double helix held by complementary base pairing: adenine with thymine, guanine with cytosine.
How did the Meselson-Stahl experiment prove DNA replication is semiconservative?
Bacteria were grown in heavy nitrogen (15N) so all their DNA was dense, then shifted to light 14N.
I keep getting “DNA structure” questions wrong in Molecular Basis of Inheritance. What's the trap?
pairing adenine with guanine or cytosine.
Why is the genetic code called degenerate, and how does that protect an organism?
There are 64 codons but only 20 amino acids, so most amino acids are specified by more than one codon (leucine has six).
What does “Semi-conservative replication” actually mean in Molecular Basis of Inheritance, and why does it matter for NEET?
each new DNA molecule keeps one original strand and one newly made strand.
In the lac operon, why are the lactose-digesting enzymes made only when lactose is present?
Normally a repressor protein sits on the operator and blocks transcription, so no enzymes are made.
I keep getting “Semi-conservative replication” questions wrong in Molecular Basis of Inheritance. What's the trap?
thinking both strands of the daughter DNA are brand new.
What does “DNA double helix” actually mean in Molecular Basis of Inheritance, and why does it matter for NEET?
two antiparallel strands held together by complementary base pairs, A with T and G with C.
What does “Transcription” actually mean in Molecular Basis of Inheritance, and why does it matter for NEET?
copying a gene's DNA into messenger RNA in the nucleus.
I keep getting “DNA double helix” questions wrong in Molecular Basis of Inheritance. What's the trap?
pairing adenine with guanine or cytosine.
I keep getting “Transcription” questions wrong in Molecular Basis of Inheritance. What's the trap?
confusing transcription (DNA→RNA) with translation (RNA→protein).
What does “Semiconservative replication” actually mean in Molecular Basis of Inheritance, and why does it matter for NEET?
each new DNA molecule keeps one old (parental) strand and one newly made strand.
What does “Translation” actually mean in Molecular Basis of Inheritance, and why does it matter for NEET?
reading mRNA codons at the ribosome to build a protein.
I keep getting “Semiconservative replication” questions wrong in Molecular Basis of Inheritance. What's the trap?
thinking both strands of a daughter molecule are freshly synthesised.
I keep getting “Translation” questions wrong in Molecular Basis of Inheritance. What's the trap?
thinking each base codes for one amino acid.
What does “Genetic code” actually mean in Molecular Basis of Inheritance, and why does it matter for NEET?
a triplet, degenerate, non-overlapping and near-universal code with AUG as start and three stop codons.
What is the difference between codon and anticodon?
A codon is a triplet of bases on mRNA that codes for an amino acid; an anticodon is the complementary triplet on tRNA that reads that codon.
I keep getting “Genetic code” questions wrong in Molecular Basis of Inheritance. What's the trap?
thinking one codon can code for several amino acids.
What is the difference between transcription and translation?
Transcription makes mRNA from DNA in the nucleus; translation makes protein from mRNA at the ribosome.
What does “lac operon” actually mean in Molecular Basis of Inheritance, and why does it matter for NEET?
in E. coli, lactose switches on the operon by inactivating the repressor so the lactose-digesting genes are transcribed.